Turbine



June 5, 1951 R. M. wlLLlAMs 2,556,020

TURBINE Filed March 25, 1946 LEI-1 Patented June 5, 1951 UNITED STATES TURBINE Robert M. Williams, Toledo, Ohio, assigner to Packard Motor Car Company, Detroit, Mich., a corporation of Michigan Application March 23, 1946, Serial No. 656,626

1 6 Claims.

This invention relates to turbines and particularly to the mounting of the high speed shaft and its operating elements in a gas turbine.

The invention is shown in connection with that type of gas turbine in which a centrifugally operating impeller is mounted at one end of a shaft and a turbine wheel is mounted at the other end thereof. In such a turbine the shaft is driven at a very high speed and it is desirabie that such shaft should be made small in diameter so that ball thrust bearings may be used, and as light as possible, and yet of sufficient strength to withstand the stresses to which it is subjected in operation. This means that in attaining the very high operating speed for which the turbine is designed it may pass through a critical speed which in sorne instances will cause the shaft to tend to move or vibrate radially which movement if not checked will possibly cause destruction of the shaft or bearings.

It is an object of the invention therefore to so mount the operating elements on the shaft and to so support the shaft in the turbine casing that the tendency to vibrate or move radially is resisted and damped or cushioned so that the mechanism may pass through the critical speed and reach the high operating speed for which it is designed.

With the above object in View, the invention provides a novel mounting of the compressor impeller on the shaft and a mounting of one of the shaft bearings so that any radial movement of the shaft in that bearing may be damped both by fiuid and friction to thereby resist radial movement.

Other objects of the invention will appear from the following description taken in connection with the drawing, which forms a part of this speoiiication, and in which:

l is a sectional View of a portion or" a gas turbine embodying the invention;

Fig. 2 is an enlarged sectional View of the interrnediate thrust bearing and associated parts and the mounting of the impeller on the shaft;

Fig. 3 is a sectional view of the sleeve which forms a part of the mounting of the inipeller on the shaft; and

Fig. l a face view of the sleeve of Fig. 3.

Referring to the drawing, lill represents'generally the casing or support of the gas turbine and il is the main operating shaft upon which are mounted a compressor mpeller li and a turbine wheel I3. These are the principal operating elements of the machine or turbine.

In the forni shown, the shaft ll is mounted in two widely separated plain bearings I4 and nediate thrust bearing But between the outer races of the ngs Il and the cup i8 there is an appreciable radial clearance of say ve-thousar1dths of an inch (.G05") or thereabouts. Thus the shaft may be said to be normally supported radially by the plain bearings ld and Iii with clearance at the inounting of the thrust bearing I6 s that the latter will not normally support the l radially at all. Bearing it however will resist end movements of the shaft and by of the clearance above referred to the bearing will perform another function as hereinafter described.

The ball bearings l? are retained in the cup i3 by of a cover lil and a plate 2G, these acting against the outer races of the bearings and through a separating ring 2i and being secured to the casing by a series of bolts 22. Clamping of the outer races of the bearings Il is sueh that there can be movement of those races radially within the limits of the clearance above referred to but at the same time this movement is frictionally resisted for a purpose hereinafter described.

There is also a separating ring 23 between the inner races of the bearings Il', and bearing against one of those inner races is a sleeve 24 which is splined to the shaft il as indicated at 'iii'. rEhe inner race of the other bearing Il rests against a shoulder 25 on the shaft Il.

The exterior of the hub portion of the sleeve 2d is threaded as at 2i and the inner portion or" the plate it is closely associated with said threaded portion so that leakage of oil from the bearings prevented or reduced.

The sleeve 2s is flanged as at 3U land on the face thereof is a series of radial grooves 3i, best shown in Figs. 3 and 4. At least three of such grooves should be provided and in the form shown herein there are eight of them. These grooves may be of semi-cyelindrioal shape as shown or rectangular or any other desired shape that will accomplish the purpose.

lThe hub of the iinpeller it is formed in its face adjacent the flange 3@ with similar or cornplenlentary grooves 32, and in the cylindrical or other shaped pockets formed by the grooves 3l, 32, a series of pins 33 are placed to bridge the space between. the hub and sleeve. Surrounding the pins 33 is a solid ring 313 retaining the pins against radial movement in the pockets. Thus it will be seen that the pin and pocket oonstruction of the flange and the hub of the impeller l2 form a denite drive connection between the shaft and the impeller, and any expansion of the impeller by r-eason of its high rotational speed will cause an all-around radial eX- pansion and the impellel` will always be maintained in a central location on the shaft.

The impeller is retained against endwise movement on the shaft by a nut shown as threaded on the shaft and when this nut is tightened the iinpelier is pressed toward the sleeve 2t, the latter clamps the bearings i'i against the shoulder 26 and all of the parts are retained in position against turning or against endwise movement on the shaft.

At the opposite end of the shaft Il the turbine wheel i3 is shown as rigidly connected to the shaft as by welding at t9.

A radial oil groove til connects with a circumferential groove 5E surrounding the cup i8 and there are a series of ports 52 in the cup and ports 53 in the ring 2i whereby oil may enter the space between the bearings i7 and thereby supply the bearings with lubricant. The ring 2l is of less diameter than the outer races of bearings il and consequently cil may flow to the clearance space between those outer races and the cup i8 thereby keeping that clearance space constantly filled. Thus the bearings il may be said to oat in the cup iS and except for the friction caused by the clamping of the cover i9, above referred to, and the resistance of the oil in the clearance space, the bearings i1 will be free to move radially.

The oil groove or passage 59 may be fed by any suitable means such as oil pump 69, and overlow of oil from the bearings may be through the opening Si at one side and the passages 62, 63 and te at the other side.

From the above it will be seen that as the shaft is speed-ed up and reaches the critical speed of 8,000 or 10,000 R. P. M., should the shaft at its intermediate point where it is supported by the intermediate bearing tend to move or vibrate radially, this movement will be resisted by the friction of the outer races of the bearings H and by the oil surrounding those races and between them and the cup i8, and this will tend to prevent the movement or dampen or cushion it so that there will be no harmful effects.

It will be understood that various forms of the invention other than that described above 'may be used without departing from the spirit or scope of the invention.

What is claimed is:

1. In a gas turbine, the combination with the turbine wheel thereof, of a casing having a bearing supporting part, a shaft for said turbine Wheel, a thrust bearing on said shaft, means forming a clearance space between the periphery of said bearing and said bearing supporting part, damping means in said clearance space, a sleeve splined to said shaft and retaining the bearing thereon, an impeller on said shaft, said impeller and said sleeve having complementary radial grooves formed in adjacent parts thereof, pins in said grooves and locking means on the shaft clamping the impeller to said sleeve through said pins.

2. In a machine, the combination of a casing having a bearing supporting part, a shaft mounted in the casing and having a shoulder, a thrust bearing on the shaft having its inner race against said shoulder and its outer race in said bearing supporting part with radial clearance therebetween, damping means in said clearance, a flanged sleeve splined to said shaft and bearing against said inner race, a wheel hub on said shaft, the face of said hub being arranged opposite a face of the ange of said sleeve, said ange and hub having a seri-es of complementary radial grooves formed in their adjacent faces, pins in said grooves, and locking means on the shaft clamping the hub through said pins to said sleeve and said inner race through said sleeve to said shoulder. Y

3. A mounting for an impeller on a shaft comprising a shaft having a shoulder, a flanged sleeve splined to said shaft against said shoulder, an impeller having a hub on said shaft, the face of said hub being arranged opposite a face of the flange of said sleeve, said iiange and face having a series of complementary radial grooves formed therein, pins in said grooves bridging the space between said sleeves and said impeller to thereby cause the impeller to rotate with the shaft, a ring for retaining the pins against radial movement, and a locking means on the shaft clamping the impeller hub to the sieeve through said pins.

4. In a gas turbine, the combination with the turbine wheel thereof, of a shaft having for said turbine wheel a shoulder, a sleeve splined to said shaft, an impeller having a hub mounted on said shaft adjacent said sleeve, said sleeve and hub having complementary radial grooves formed in adjacent surfaces, pins in said grooves, means retaining the pins against radial movement, and locking means on the shaft clamping the impeller to the sleeve through said pins.

5. yIn a high speed shaft mounting, the combination of a support, two widely separated bearings in said support, a shaft mounted in said bearings and free to move axially therein, an intermediate bearing for said shaft in said support, said intermediate bearing have its parts so connected to the shaft and said support that bodily axial movement of the shaft either direction in said support is prevented, said intermediate bearing parts having radial clearance in said support, and liquid means in said clearance tending to damp radial'moveinent of said shaft.

6. In a high speed shaft mounting, he combination of a support, two widely separated bearings in said support, a shaft mounted in said bearings and free to move axially therein, an intermediate bearing for said shaft in said support, said intermediate bearing having its parts so connected to the shaft and said support that bodily axial movement of the shaft in either direction in said support is prevented, said intermediate bearing parts having radial clearance in said support, and liquid means in said clearance and friction means combined therewith tending to damp radial movement of said shaft.

ROBERT M. LLAM REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 656,310 Warburton Aug. 21, 1900 1,812,973 Miller July 7, 1931 2,012,997 Junkers Sept. 8, 1935 2,403,878 Schmidt July 9, 1946 

